1. Field of the Invention
The present invention relates to a picture recording apparatus and, more particularly, to an apparatus for producing a hard copy of a picture which is represented by video signals.
2. Description of the Prior Art
Today, there is a demand for an apparatus which allows picture picked up by an electronic still camera or a television (TV) camera and stored in a magnetic disk adapted for pictures, or so-called video floppy, a video tape or like video signal recording medium to be reproduced in the form of hard copies, i.e., to be recorded in printing papers and other recording media as visible pictures. Desirably, such a recording apparatus should enable a person to see the conditions of a desired picture before actually recording it.
Generally, a predominant type of signal system in the video equipment art is an interlace scanning system in which the number of scanning lines is 525 and the field frequency is 60 hertz as based on the NTSC (National Television Systems Committee) and other common color TV standards. Such standards prescribe that one frame consists of two fields and one field consists of 262.5 scanning lines.
A picture recorded in a printing paper by shooting the screen of a cathode ray tube (CRT) on which a picture being displayed by interlace scanning is apt to suffer from conspicuous pairing of scanning lines due to incomplete interlace scanning. The pairing on the picture is far more significant on a hard copy, or printing paper, than on a soft copy which may be reproduced on a CRT screen.
In light of the above, very severe conditions against pairing should be imposed on recording of a picture which is displayed on a CRT. Therefore, in order that a video signal produced by interlace scanning may be directly used for shooting on the screen, it is necessary that a high-tension circuit adapted to drive the CRT be provided with sufficient stability grading up the circuit to a prohibitive degree.
The pairing problem may readily and surely be solved if the interlace scanning system is replaced with a non-interlace scanning system, i.e. sequential scanning system. However, where a non-interlace scanned picture is displayed on a monitor to meet the demand as previously stated, flicker appears so conspicuously that the picture is not worth seeing. The flicker cannot be eliminated without raising the frame frequency far beyond the ordinary 60 hertz or 30 hertz, again grading up the associated circuits.
Generally, video signals under a wide variety of conditions are entered into a hard copy recording apparatus and, therefore, the signal level is distributed over a considerable range. Such a signal level distribution is quite probable in pictures picked up by, for example, an electronic still camera because an automatic exposure mechanism built in an electronic still camera lacks precision. Moreover, many of the pictures picked up by an electronic still camera involve various shooting conditions other than standard ones. It follows that the colors, density, tone and other factors of a picture must be corrected in order to allow the picture being reproduced to appear as natural as an actual scene picked up. The prerequisite is, therefore, that where a picture represented by video signals is to be reproduced as a hard copy such as a print, a person be capable of compensating the video signals while watching a monitor as has been the case with a prior art video color analyzer.